Conductive shoe



R. W. PRICE CONDUCTIVE SHOE Oct. 21, 1958 2 Sheets-Sheet 1 Filed April11. 1955 Fig. 3

INVENTOR. Russell W. Price ATTORNEY 0a. 21, 1958 R. w. PRICE 2,857,556CONDUCTIVE SHOE Filed April 11, 1955 v 2 Sheets-Sheet 2 Fig.7

INVENTOR. Russell W. Price l. JM maul-Leg A T TORNE Y ten 2,857,556Patented Oct. 21, 1958 CONDUCTIVE SHOE Russell W. Price, Newton, Mass.Application April 11, 1955, Serial No. 500,323

7 Claims. (Cl. 317-2) This invention relates to a conductive shoe.

The invention has for an object to provide a novel and improvedconductive shoe arranged to establish a grounded connection between thebody of the wearer and a grounded floor or surface to the end thatstatic electric charges may be discharged harmlessly through theconductive shoe and into the grounded floor or other surface whereby therisk of explosion as the result of static spark from the wearer may bereduced to a minimum.

With this general object in view and such others as may hereinafterappear the invention consists in the conductive shoe hereinafterdescribed and particularly defined in the claims at the end of thisspecification.

In the drawings illustrating the preferred embodiment of the invention:

Fig. 1 is a side elevation, partly in cross section, of a conductiveshoe embodying the present invention;

Fig. 2 is a plan view of the insole shown in Fig. 1;

Fig. 3 is a side elevation of the insole;

Fig. 4 is a plan view of the outer sole portion of the shoe shown inFig. 1;

Fig. 5 is a side elevation of the same;

Fig. 6 is a cross sectional view taken on the line 66 of Fig. 1;

Fig. 7 is a side elevation, partly in cross section, of a modified formof conductive shoe embodying the present invention;

Fig. 8 is a perspective view of the insole shown in Fig. 7;

Fig. 9 is a perspective view of the outer sole portion of the shoe shownin Fig. 7; and

Fig. 10 is a cross sectional view taken on the line 1tl10 of Fig. 7.

In general the present invention contemplates an electrically conductiveshoe adapted to be worn by persons in places where explosives orvolatile liquids are present and which are particularly adapted to beworn by surgeons and other hospital personnel in an operating room whereexplosive vapors and gases from volatile inflammable liquid anesthetics,such as ether, may be ignited by sparks produced by the discharge ofstatic electric charges built up in the body of the person. Theillustrated conductive shoe may and preferably will include a conductiveouter sole of relatively soft, flexible material, such as a conductiverubber outer sole and a relatively thin and flexible conductive metallicfoil strip secured to the upper surface of the insole for contact withthe foot of the wearer, and means for electrically connecting themetallic foil with the conductive rubber outer sole of the shoe. Thus,in accordance with the present invention static electric charges may beslowly dissipated and harmlessly discharged from the body of the personthrough the conductive shoe and into the grounded conductive floor ofthe hospital operating room. An important advantage of the presentconstruction of conductive shoe resides in the provision of therelatively thin conductive metallic foil strip which may and preferablywill comprise a laminated or reinforced aluminum foil strip secured tothe insole for contact with the foot of the wearer, such metallic stripbeing relatively smooth and non-absorbent so as to retain itsconductivity over long periods of time. The conductive metallic foil mayand preferably will be laminated with a relatively thin strip of plasticsheet material characterized by being diificult to tear, thus forming atough reinforcing base for the metal foil preventing rupture undersevere conditions of use. Prior conductive shoes of which I vam awareare usually provided with conductive rubber insoles for contact with thefoot of the wearer, and after a period of time such conductive rubberinsoles lose their conductivity on the upper surface thereof uponbecoming soiled, which in effect provides a non-conductive film on theupper surfaces of such prior insoles, thereby greatly reducing theirconductive characteristics.

Referring now to the drawings, 10 indicates generally the conductiveshoe embodying the present invention and which includes a conductiverubber outsole 12 secured to a mid-sole or filler portion 14, and thenumeral 16 represents the insole or sock lining which may comprisesponge rubber or other non-conductive material. The conductive rubberoutsole 12 extends over the entire area of the bottom of the shoeincluding the heel portion. The upper surface of the insole 16 isprovided with a flexible conductive metallic foil portion 18 securedthereto, the foil portion extending from a point immediately in front ofthearch portion of the instep rearwardly to the end of the heel portionof the insole. As illustrated in Fig. 2, the metallic foil portion 18 isprovided with a lateral extension 20 which may be folded downwardly andinwardly around one edge of the insole to provide an integral conductivesurface on the underside of the insole immediately above the center ofthe arch portion. It will also be observed that the insole 16, includingthe conductive foil member 18 attached thereto, is provided witharounded lateral extension 21 adjacent the arch portion which in theassembled form, as shown in Figs. 1 and 6, is arranged to extendupwardly a short distance whereby to assure firm engagement with thewearers foot adjacent the arch portion at all times.

As illustrated in Fig. 6, the upper or body portion of the shoeindicated at 22 may be stitched or otherwise secured to the mid-sole 14as indicated at 24, and a nonconductive filler member 26 may be providedbetween the mid-sole 14 and the insole 16. In order to provide anelectrical connection between the conductive metal foil 18 of the insoleand the conductive rubber outsole 12, a metal rivet 36, which maycomprise copper or other conductive metal, is extended through anopening 32 formed at the center of the arch portion, the lower end ofthe rivet embracing and having electrical contact with the conductiverubber outer sole 12. The upper end of the rivet extends through themid-sole 14 and the filler member 26 and embraces the upper surface ofthe filler member. Thus, the head 27 at the upper end of the rivet isarranged to frictionally engage the lateral extension 20 on theunderside of the insole 16 to make electrical contact therewith asshown. In practice the exposed head of the lower end of the rivet mayand preferably will be covered by a plug of conductive rubber 31vulcanized thereto and to the adjacent surfaces of the outer sole asshown.

In order to further assure firm electrical contact between the metallicconductive foil strip 18 of the insole and the conductive rubber outsole12 over a relatively large area, a pair of elongated conductive foilstrips 28, 30 are provided, one strip 28 extending from an inter mediateportion corresponding to the ball of the foot be tween the insole 16 andthe filler member 26, then passing under one edge of the head 27 of therivet and downwardly through the opening 32 along the length of therivet, the other end of the strip 28 being folded back and extendedtoward the toe portion between the underside of the midsole and theinner surface of the conductive rubber outsole asshown. The otherelongated conductive metal strip 30.may be similarly extended betweenthe insole 16 and the filler member 26 from the heel portion, throughthe opening 32 in conducting engagement with the rivet 36 and rearwardlybetween the mid-sole and the conductive rubber out-sole toward the heelportion. With this construction it will be seen that the foil strips 28,30 arein electricalcontact with the rivet 36 and the outsole 14 and thatthelateral extension 20 on the underside of the insole is also inelectrical contact with portions of the strips 28, 30.0n both sides ofthe upper head portion 27 of the rivet as indicated at 33, 35 in Fig. l.

Referring now to Fig. 7, in a modified form of the present invention theconductive shoe is provided with an outer sole of relatively soft,flexible material, such as a conductive rubber outer sole 40 providedwith integral lateral extensions or straps 42, 44 adjacent the archportion of the instep of the shoe, such conductive straps being foldedupwardly and inwardly in overlapping relation about a non-conductivemid-sole portion 46. The outer edges of the shoe may be provided with anonconductive rubber trim portion 48 which may extend inwardly for ashort distance over the edges of the upper surface of the mid-sole andover filler pieces t provided along the edgesof the mid-sole. The upperportions 52 of the shoe may be stitched or adhesively secured to themid-sole toprovide the structure shown in Fig. 10. The insole 54, whichmaycomprise a non-conductive material, such as sponge rubber, isprovided with a relatively thin, flexible metallic conductive strip 56,preferably a 1aminated aluminum foil strip, extended longitudinally ofthe insole, and a conductive rubber strap 58 is wrapped about the archportion of the insole in electrically conductive engagement with theupper surface of the strip 56, the ends of the strap 58 being arrangedin overlapping relation on the underside of the insole whereby theoverlapping portions 55,57 of the strap 58 engage with the overlappingportions of the lateral extensions 42, 44 of the outsole 40. In practicethe conductive rubber portions of the shoe are asembled in an uncuredform, and upon assembly the conductive rubber portions of the shoe,

including the area adjacent the arch portion of the instep of the shoe,are vulcanized together so as to form a permanent integralconductivebond from the upper surface of the conductive metal strip through theinsole conductive rubber strap 58, and the overlapping lateralextensions 42, 44 to the outsole 40. The conductive metal strip 56 mayand preferably will comprise a laminated strip adhesively secured to theupper surface of the insole 54, andthe -conductive rubber insole strap58 may be adhesively secured tothe upper surface of the metallic strip56 with a conductive rubber cement.

In practice the conductive metallic strip embodied in the presentinvention may comprise a relatively thin aluminum foil in the order of.001 to .002 in thickness which may and preferably will be laminated toa sheet of polyester plastic film, such as that sold under the tradename of Mylar, characterized by its non-tearing qualities whereby toreinforce the relatively thin foil strip and render it less subject tobeing torn or ruptured in use. In practice the laminated foil strip maybe secured to the upper surface of the insole with any suitableadhesive, such as a pressure sensitive adhesive.

From the above description it will be seen that the present conductiveshoe may be used with advantage by surgeons, nurses and other attendantsin operating rooms where the fumes of ether or other combustible vaporsor gases are apt to be present, such shoes permitting a slow dissipationand continuous discharge of static electricity from the wearers. bodythrough the shoe and into a grounded conductive floor of;the-,operatingroom. The

rubber trim portion 48 extending around the edge of the shoe may andpreferably will be of non-conductive rubber and serves as a scufi guardto prevent scufling of the floors by the conductive rubber portion ofthe shoe. It will also be observed that the conductive aluminum foilforming the conductive surface between the foot of the wearer and theshoe is relatively thin so as not to interfere with the comfort of thewearer and has the further advantage of retaining its electricalconducting qualities over a considerable period of time.

While the preferred embodiment of the invention has been hereinillustrated and described, it will be understood that the invention maybe embodied in other forms within the scope of the following claims.

Having thus described the invention, what is claimed l. A conductiveshoe comprising an outer sole of conductive rubber, a non-conductiveinsole having a metal foil conductive strip secured to the upper surfacethereof for contact with the wearers foot, and means for electricallyconnecting said conductive foil strip to the conductive rubber outersole, said metal foil conductive strip being of a thickness of the orderof a few thousandths of an inch and having a thin, tough plasticreinforcing strip laminated to its underside to prevent tearing and thedevelopment of wrinkles in the foil when the shoe is worn.

2. A conductive shoe comprising a non-conductive mid-sole extending thefull length of the shoe and having a sole portion, a heel portion and araised instep portion,

said mid-sole being provided with an outer sole of conductive rubbersecured thereto and entirely covering the bottom and marginal edges ofsaid midsole, an insole having a flexible metal foil conductive stripsecured to the upper surface thereof for contact with the wearers foot,said metal foil strip of a thickness of the order of a few thousandthsof an inch and having a lateral extension folded around one edge andsecured to the underside of said insole adjacent the arch portion of theinstep, and a metal conducting member disposed beneath the insole andextended through an opening in said arch portion and in conductingengagement with said outsole and with said lateral extension on theunderside of the insole, said metal conducting member and the adjacentportion of the conductive outer sole disposed in said raised instepportion being free of contact with the ground when worn.

3. A conductive shoe as defined in claim 2 wherein a pair of additionaland similar elongated flexible metal foil conducting strips are extendedlongitudinally of the shoe between the insole and the mid-sole, throughsaid opening, and between the mid-sole and the outer sole, saidadditional metal strips being in conducting engagement with said lateralextension, metal conducting member and outer sole, the lower end of saidmetal conducting member having a conductive rubber covering vulcanizedto the adjacent portion of the conductive rubber outer sole.

4. A conductive shoe comprising an outer sole of conductive rubber, anon-conductive insole having a flexible metal conductive foil stripsecured to the upper surface thereof for contact with the wearers foot,said foil being of a thickness of the order of a few thousandths of aninch, and conductive rubber connections between said conductive metalstrip and said outer sole, said conductive rubber connections includingconductive rubber extensions from said insole in contact with said metalfoil strip, and conductive rubber extensions from said outer sole and incontacting relation to said first named extensions, said extensionsbeing vulcanized together in the assembled shoe to form an integralconductive rubber bond between the outer sole and the upper surface ofsaid conductive metal foil strip.

5. A conductive shoe comprising an outer sole of conductive rubber, anon-conductive insole having a flexible metal conductivefoilstripsecured to the upper surface thereof for contact with thewearers foot,said conductive foil strip being of a thickness of the order of a fewthousandths of an inch, and conductive rubber connections between saidconductive metal strip and said outer sole, a non-conductive mid-soledisposed between said outer sole and said inner sole, said conductiverubber connections including a conductive rubber strap secured to theupper surface of said metal strip and wrapped about the underside of theinsole adjacent the arch portion, said outer sole having laterallyextended conductive rubber straps wrapped about the upper surface ofsaid mid-sole adjacent the arch portion and in contacting engagementwith the strap Wrapped about the underside of the insole, the contactingportions of the insole strap and the outer sole straps being vulcanizedtogether in the assembled shoe to form an integral electricallyconductive rubber bond between the outer sole and the upper surface ofthe conductive metal foil strip.

6. A conductive shoe comprising an outer sole of conductive rubberextending the full length of the shoe and having a sole portion, a heelportion and a raised instep portion, a non-conductive insole, aconductive metal foil having a thin, tough plastic reinforcing striplaminated to its underside and secured to and conforming to the uppersurface of the non-conductive insole and of a thickness of the order ofa few thousandths of an inch, and means for establishing electricalconnection between the metal foil and the conductive outsole.

7. A conductive shoe as defined in claim 6 wherein said foil covers aportion only of the upper surface of the insole and wherein theelectrical connection between the foil and the outsole is disposed atthe instep portion of the shoe out of contact with the ground when theshoe is worn.

References Cited in the file of this patent UNITED STATES PATENTS495,782 Carnes Apr. 18, 1893 497,822 Rayer May 23, 1893 871,479 CooperNov. 19, 1907 884,681 Reed Apr. 14, 1908 2,261,072 Monahan Oct. 28, 19412,710,366 Stern June 7, 1955 2,712,099 Legge June 28, 1955

